Question

The ion of an element has 3 positive charges. The mass number of atom of this element is 27 and the number of neutrons is 14. What is the number of electrons in the ion?

Answer 1

Mass number of atom = 27
Number of neutrons = 14
Number of protons = Mass number$-$Number of neutrons
Number of protons = 27$-$14
Number of protons = 13

As the number of protons = Number of electrons
So, Number of electrons = 13
But the element has 3 positive(+3) charge that means this element has the deficiency of 3 electrons.
So, Number of electrons = 13$-$3 =10

Hence, the number of electrons in the given ion is 10.